Optimal measurement configurations for kinematic calibration of six-DOF serial robot

An optimal measurement pose number searching method was designed to improve the pose selection method.Several optimal robot measurement configurations were added to an initial pre-selected optimal configuration set to establish a new configuration set for robot calibration one by one.The root mean squares (RMS) of the errors of each end-effector poses after being calibrated by these configuration sets were calculated.The optimal number of the configuration set corresponding to the least RMS of pose error was then obtained.Calibration based on those poses selected by this algorithm can get higher end-effector accuracy,meanwhile consumes less time.An optimal pose set including optimal 25 measurement configurations is found during the simulation.Tracking errors after calibration by using these poses are 1.54,1.61 and 0.86 mm,and better than those before calibration which are 7.79,7.62 and 8.29 mm,even better than those calibrated by the random method which are 2.22,2.35 and 1.69 mm in directions X,Y and Z,respectively.

Inverse displacement analysis of the general six degree-of-freedom serial robot based on optimization method

The paper presents a new solution of inverse displacement analysis of the general six degree-of-freedom serial robot.The inverse displacement analysis of the general serial robot is transformed into a minimization problem and then the optimization method is adopted to solve the nonlinear least squares problem with the analytic form of new Jacobian matrix.In this way,joint variables of the general serial robot can be searched out quickly under the desired precision when positions of the three non-collinear end effector points are given.Compared with the general Newton iterative method,the proposed algorithm can search out the solution when the robot is at the singular configuration and the initial configuration used in the optimization method may also be the singular configuration.So the convergence domain is bigger than that of the general Newton iterative method.Another advantage of the proposed algorithm is that positions of the three non-collinear end effector points are usually much easier to be measured than the orientation of the end effector.The inverse displacement analysis of the general 6R(six-revolute-joint) serial robot is illustrated as an example and the simulation results verify the efficiency of the proposed algorithm.Because the three non-collinear points can be selected at random,the method can be applied to any other types of serial robots.

Application of Task-Oriented Method of Serial Robot for Mechanism Analysis and Evaluation

Revealing the relations among robotic comprehensive performance,configuration,scales and working tasks is the basis to optimize robotic mechanism. Due to the correlation and diversity of the single performance indexes,statistical principles of linear dimension reduction and nonlinear dimension reduction are introduced into comprehensive performance analysis and evaluation for typical serial robot. The robotic mechanism's configuration,scales and task with the best comprehensive performance can be obtained by principal component analysis( PCA) and kernel principal component analysis( KPCA) respectively. The results show that KPCA can reveal the nonlinear relations among different single performance indexes more effectively and provide more comprehensive performance information than PCA. Thus,task-oriented method of serial robot for mechanism analysis and evaluation is proposed,which also provides scientific research basis for the mechanism synthesis and optimum task order.

A New Solution to the Inverse Position Analysis of the Redundant Serial Robot

A new solution to the inverse position analysis of the redundant serial robot is presented.The inverse position analysis problem of the redundant serial robot is transformed into a minimization problem and then the optimization method is adopted to solve the nonlinear least square problem with the analytic form of a new Jacobi matrix.In this way,the inverse solution of the redundant serial robot can be searched out quickly under the desired precision when the positions of the three non-collinear end effector points are given.The inverse position analysis of the 7R redundant serial robot is illustrated as an example and the simulation results verify the efficiency of the proposed algorithm.

Optimization of Serial Port of General Flex Pendant for Industrial Robot

In order to further improve the serial ports communication mode of the general Flex Pendant for industrial robot,a multiple serial communication mode is put forward. It is used to meet the stability of data transmission,transmission distance,transmission speed,anti-interference and cost-effective. Using ADUM1201 single direction dual channel digital isolator,two pieces of MAX13487 E and a piece of MAX3232 chip to transmit data and files, and to control chip’ s electrical level. Selecting the RS232, RS422 and RS485 communication mode,the serial ports of the general Flex Pendant of industrial robot is optimized.

基于POE模型的工业机器人运动学参数二次辨识方法研究

针对工业机器人在高度制造领域精度不高的问题,本文提出了一种基于POE模型的工业机器人运动学参数二次辨识方法。阐述了基于指数积(Product of exponential, POE)模型的运动学误差模型构建方法,并建立基于POE误差模型的适应度函数;为实现高精度的参数辨识,提出了一种二次辨识方法,先利用改进灰狼优化算法(Improved grey wolf optimizer, IGWO)实现运动学参数误差的粗辨识,初步将Staubli TX60型机器人的平均位置误差和平均姿态误差分别从(0.648 mm, 0.212°)降低为(0.457 mm, 0.166°);为进一步提高机器人的精度性能,再通过LM(Levenberg-Marquard)算法进行参数误差的精辨识,最终将Staubli TX60型机器人平均位置误差和平均姿态误差进一步降低为(0.237 mm, 0.063°),机器人平均位置误差和平均姿态误差分别降低63.4%和70.2%。为了验证上述二次辨识方法的稳定性,随机选取5组辨识数据集和验证数据集进行POE误差模型的参数误差辨识,结果表明提出的二次辨识方法能够稳定、精确地辨识工业机器人运动学参数误差。

Research of 6-DOF Serial-Parallel Mechanism Platform for Stability Training of Legged-Walking Robot

The concept of legged-robot stability training with a training platform is proposed and a serial-parallel mechanism platform with 6 degrees of freedom is designed for this target. The designed platform is composed of 4-DOF parallel mechanism with spherical joints and prismatic pairs,and 2-DOF serial mechanism with prismatic pairs. With this design,the platform has advantages of low platform countertop,big workspace,high carrying capacity and high stiffness. On the basis of DOF analysis and computation of space mechanism,weight supporting auxiliary mechanism and raceways-balls supporting mechanism are designed,so as to improve the stiffness of designed large platform and payload capacity of servo motors. And then the whole structure design work of the platform is done. Meanwhile,this paper derives the analytical solutions of forward kinematics, inverse kinematics and inverse dynamics. The error analysis model of position and orientation is established. And then the simulation is done in ADAMS to ensure the correctness and feasibility of this design.

基于NSGA-Ⅱ的串联机器人几何参数公差的多目标优化分配

为了提高机器人末端执行器的几何定位精度,在机器人精度的初始设计阶段合理分配几何参数公差,提出了一种带精英策略的快速非支配排序遗传算法(NSGA-Ⅱ)的以成本与精度为目标的多目标公差优化分配方法.以ROKAE XB7型6自由度串联机器人为研究对象,分别基于遗传算法(GA)的最小成本单目标公差优化分配方法和NSGA-Ⅱ的多目标公差优化分配方法对DH(Denavit-Hartenberg)参数的公差优化分配.在精度设计目标和遗传算法参数设置相同的情况下,与基于遗传算法的最小成本的几何参数公差优化分配相比,基于NSGA-Ⅱ的多目标公差优化分配能够给出不同制造成本和不同精度设计要求的一系列最优解,在得到同等制造成本和机器人精度的情况下,公差的容错松弛率相对较高,参数公差优化分配的结果更优.

基于螺旋理论的串联机器人奇异性分析

串联机器人被广泛用作工业机器人、医疗机器人等。当处于奇异位姿时,串联机器人将变得自由度减少或不可控。文中利用螺旋理论,提出一种对串联机器人奇异性进行分析的方法。文中提出的奇异性分析方法,不需要求导运算,物理意义明确。

基于螺旋理论的非冗余并联机器人奇异性分析

并联机器人被广泛用作运动模拟平台、振动台和并联机床等。当处于奇异位姿时,并联机器人将变得自由度减少、自由度类型改变或自由度增多等,致使内力增大、达不到需要的运动或不可控等。文中利用螺旋理论,提出一种对非冗余并联机器人奇异性进行分析的方法。该奇异性分析方法不需要求导运算,物理意义明确。

移动机器人导航路径的异构串行蚁群算法规划

为了减少机器人工作路径长度和拐点数量,提出了基于异构串行蚁群算法的路径规划方法。介绍并改进了栅格模型的投影、膨化和编码过程;以减少工作路径长度和拐点数量为目标,建立了机器人导航路径的优化模型。分析了标准蚁群算法原理,依据起点和目标点位置的先验知识,引入了信息素非均匀初始化方法;在概率公式中添加了角度启发因子;并在蚁群中加入具有全局通视能力的蚂蚁,提出了异构蚂蚁串行策略。在(10×10)和(20×20)规模栅格中,将异构串行蚁群算法用于机器人路径规划,与标准蚁群算法和文献[12]超强启发算法相比,异构串行蚁群算法规划路径长度最短,且拐点数量远小于另外两种算法。仿真结果表明异构串行蚁群算法在机器人路径规划中具有优越性。

DESIGN OF A NOVEL DEXTEROUS ROBOT HAND

In the robotic community more and more hands are developed. Based on theexperience of HIT Hand and DLR Hand II, a smaller and easier manufactured dexterous robot hand withmultisen-sory function and high integration is jointly developed. The prototype of the hand issuccessfully built. It has 4 fingers in total 13-DOFs (degree of freedom). Each finger has 3-DOFsand 4 joints, the last 2 joints are mechanically coupled by means of four-bar linkage mechanism. Italso has an additional DOF to realize motion of the thumb relative to the palm. The fingertip forcecan reach up to 10 N. Full integration of mechanical body, actuation system, multisensory system andelectronics is a significant feature. DSP based control system is implemented in PCI busarchitecture and the serial communication between the hand and DSP needs only 2 lines.

一种仿生四足机器人腿部机构的运动学分析与验证

提出了一种用于仿生四足机器人的新型串并混联腿部机构。首先介绍了四足机器人的结构组成,然后基于矢量分析法推导了该串并混联腿部机构的运动学正解与反解方程,并采用蒙特卡洛法求解了机器人腿部机构的工作空间,求出腿机构的速度雅克比矩阵。最后引入基于零冲击原则的足端轨迹,采用Adams软件对机器人单腿模型进行了虚拟样机仿真。仿真结果表明:各驱动电缸的速度变化曲线与理论计算结果一致,误差在±1×10^(-3)m/s范围内,验证了机器人运动学模型的正确性,间接验证了机器人位置方程和工作空间求解的正确性,为腿部机构的静力学分析和动力学分析及整机结构优化奠定了基础。

考虑能耗的仿生软夹生产线瞬态性能分析

面向2035的高端装备制造以智能化、少人化和绿色化作为其重要指标,而仿生机械具有可植入工业控制算法、可替代传统人工的特点,使其受到了广泛关注。软夹是仿生机械手臂的核心组件,由包含聚二甲基硅氧烷(PDMS)和碳纳米管(CNT)材料的双层材料复合加工而成。为了生产具有较高定制化特性的软夹部件,其制造过程通常采用多台3D打印机串接的方式进行。而此类加工设备能耗较高,因此软夹生产需同时考虑产出率和能源消耗。针对典型仿生软夹生产系统,构建了双伯努利机器串行生产线模型,并得到其瞬态性能分析与期望能耗的计算公式,可用于求解该生产系统的瞬时生产率、原材料消耗率、在制品数量以及设备的饥饿率和阻塞率。根据设备工况提出了两种不同的控制策略用于降低实际生产过程中的设备耗能,并设计了数值算例以比较不同策略对生产系统能耗的影响。此外,通过建立产线的仿真模型,进一步验证了该理论算法的有效性。

A calibration and compensation method for an industrial robot with high accuracy harmonic reducers

Industrial serial robots need high stiffness to keep absolute pose accuracy and meet the requirements in practical applications. However, the weak stiffness feature of robot joints and the payloads affected on robot end-effector, which will also increase the pose error of robot. Especially, the existing calibration methods often consider under no-payload condition without discussing the payload state. In this paper, we report a new industrial serial robot composed by a new harmonic reducer: Model-Y, based on high accuracy and high stiffness, and a kinematic parameter calibration algorithm which is based on a harmonic reducer forcedeformation model. To decrease the accuracy effects of payload, an iterative calibration method for kinematic parameters with payload situation was proposed. Simulation and experiments are conducted to verify the effectiveness of the proposed calibration method using the self-developed industrial serial robot. The results show a remarkably improved accuracy in absolute position and orientation with the robot's payload range. The position mean error has 70% decreased to 0.1 mm and the orientation mean error diminished to less than 0.01° after calibration with compensation. Additionally, online linear and circular tests are carried out to evaluate the position error of the robot during large-scale spatial and low-speed continuous movement. The accuracy is consistent with the previous calibration results, indicating the effectiveness and advantages of the proposed strategy in this article.

考虑温度影响的机器人关节摩擦模型

为描述连续运转下的温度对串联机器人关节摩擦的影响,提出一种考虑温度影响的关节摩擦模型。该摩擦模型可在无需对温度进行测量或估计的前提下描述关节温度变化对关节摩擦的影响。通过实验测量了机器人关节在不同角速度下连续运转时的摩擦力矩,并基于理论模型对数据进行了拟合。实验结果对比验证了该关节摩擦模型的有效性,且该模型能较为准确地描述连续运转下关节摩擦力矩的变化。

串联机器人机械臂工作空间与结构参数研究

工作空间的体积可以反映串联机器人运动灵活程度。研究了一种串联机器人机械臂的工作空间问题。首先,提出机械臂的基本结构,进行简化,得到其运动模型;在此基础上对机械臂进行了运动学分析;然后,采用蒙特卡洛法分析该机械臂的工作空间,得出了机械臂末端的工作空间点云图;提出了自适应划分网格方法,并用该方法计算了该工作空间的体积;最后,分析了机械臂结构参数对工作空间体积的影响,为机械臂的参数优化提供了理论依据。

基于旋量理论的串联机器人逆解子问题求解算法

为了提高串联机器人逆运动学的求解效率,明确逆解的几何意义,提出基于旋量理论的逆运动学子问题求解算法.该子问题描述为"绕3个不相交轴旋转(其中2个轴线平行,且与第3个轴异面)".以6自由度串联机器人"钱江一号"为例,通过旋量理论及指数积(POEs)方程来建立运动学模型,给出该新型逆运动学子问题的求解方法.将整体逆运动学问题分解为该类子问题和其他已知的Paden-Kahan逆运动学子问题来联合求解.通过实例验算证明,该逆运动学子问题的求解方法高效可靠,具有明显的几何意义,能够满足机器人的强实时系统控制要求.

基于摩擦模糊建模与补偿的机器人低速控制

针对摩擦引起机器人低速时运动性能恶化、作业精确度变差的问题,提出考虑负载力矩影响的摩擦模糊建模方法及模糊自适应鲁棒控制策略。通过摩擦测量实验,提取关节摩擦随负载力矩变化的特征,并提出一种扩展摩擦模型以描述关节摩擦特性。为克服固定补偿难以处理摩擦不确定性的弱点,引入模糊逻辑系统逼近摩擦现象,并实现模型的线性化以设计自适应学习机制。在此基础上,设计模糊自适应鲁棒控制算法,该算法采用前馈的方式补偿关节摩擦的影响,自适应项实现参数的在线调整,并根据系统中不确定性的界,设计鲁棒控制项以保证系统的鲁棒性。对比实验结果表明,所提出的摩擦模型与控制算法使关节最大跟踪误差可控制在0.005°以内,与未考虑负载力矩影响的控制器相比,平均跟踪误差和最大跟踪误差分别降低了25%、14.55%。

一种串联机器人的随机误差分析方法

利用旋量理论,通过定义关节处的误差运动旋量,建立了包含结构参数误差的串联机器人误差模型.在此基础上,提出了一种将Monte Carlo方法与串联机器人误差模型相结合的随机误差分析方法,用于揭示机器人末端位姿误差的概率特性.并以直角坐标装配机器人为例,在Matlab软件环境中进行了仿真,得到了机器人末端随机位置误差在工作空间内的分布规律.仿真结果表明,该方法正确、有效,仿真得到的随机误差特性对标定精度的提高以及最优工作空间的选择具有重要意义.